Arrow 71777MI Stainless Steel Racing De-cat Headers – BMW F 750 GS and F 850 GS 2021-2024

The Arrow 71777MI racing headers replace the original header assembly on the BMW F 750 GS and F 850 GS 2021-2024 (Arrow vehicle type MG85, Euro 5). They are made of stainless steel, remove the catalytic converter, retain the lambda sensor housing, and weigh 1.82 kg. The 50 mm outlet connects directly to the Arrow 71776MI mid-pipe. Part number 71777MI, EAN 8019799122505.

✓ Strengths

• Removes the catalytic converter – eliminates the most restrictive element of the stock system, freeing up exhaust gas flow
• Stainless steel – resists corrosion and high temperatures in the hottest part of the system
• Lambda sensor housing retained – the original sensor can be reinstalled in its place, no blind attachment remains
• 1.82 kg – weight declared by Arrow for the complete assembly
• 50 mm outlet – the same measurement as the Arrow 71776MI mid-pipe connection: the two pieces connect without adapters
• Interchangeable with original parts – can also be installed while keeping the stock muffler
• Dual application – the same code applies to F 750 GS and F 850 GS 2021-2024

Technical specifications

Data from the official Arrow SPECIFICATIONS sheet for code 71777MI.

Arrow publishes 0.00 for body length and inlet diameter: these are uncompiled values, not real measurements, and therefore we do not report them.

Vehicle compatibility

For F 800 GS and F 900 GS 2024-2026 (vehicle type MG90), Arrow does not produce headers: on those motorcycles, the upstream part is only the mid-pipe. Always check model and year before purchasing.

How they fit into the system

They are the first section of the system, connected to the cylinder head. Downstream, the Arrow 71776MI mid-pipe (also racing, 50 mm connection) and then the muffler are mounted. All Arrow components are interchangeable with original ones, so the headers can also be used with the stock muffler.

🔑 The 72639AKN muffler alone is ECE homologated and keeps the motorcycle road legal. Adding racing headers or mid-pipe makes the system usable only on closed circuits.

Perfect for

For those who take their F 750 or F 850 GS to the track or closed circuits and want to truly free up the system: the muffler alone changes the sound, but as long as the catalytic converter remains in place, that's the bottleneck. These headers remove that restriction and lighten the front of the system, while remaining mountable even with the original muffler. This is a part purchased with the understanding that the motorcycle, in this configuration, is not for road use.

Frequently asked questions

Are they road legal?
No. Arrow marks them Racing on both model pages, and the official legend states that a Racing product does not comply with any regulations and should only be used on closed circuits. By removing the catalytic converter, the motorcycle is not legal for road use or inspection.

Which BMWs do they fit?
On F 750 GS and F 850 GS from the 2021-2024 series, which Arrow identifies with vehicle type MG85. For F 800 GS and F 900 GS 2024-2026 (MG90), Arrow does not produce headers.

Can I install them while keeping the original muffler?
Yes. All Arrow components are interchangeable with stock parts, so the headers can be combined with the original muffler or an Arrow muffler.

Can the lambda sensor be reinstalled?
Yes: Arrow states that the lambda sensor housing is present on the headers, so the original sensor will find its connection point. However, there is no housing for the CO sensor.

How much do they weigh and what is their diameter?
1.82 kg and 50 mm outlet diameter, the same measurement as the 71776MI mid-pipe connection. Length and inlet diameter are not among the data published by Arrow, so we do not report them.

Which muffler do they combine with?
With the Maxi Race-Tech 72639AKN, via the 71776MI mid-pipe. Please note: the muffler alone is ECE homologated, but with racing headers and mid-pipe, the system becomes for track use.

Is it an original product?
Yes, original Arrow Special Parts spare part, code 71777MI, EAN 8019799122505.